I. Field of the Invention
The present invention relates generally to conditioning and rehabilitation apparatus for controlling and developing body movements and, more particularly, to a device which is positioned under the foot to develop and retrain the ankle and its associated body parts.
II. Description of the Prior Art
The ankle is commonly known as the joint between the lower leg and the foot. The anatomical structure of the ankle includes a bone structure, muscles and tendons, ligaments and a neurological system. Typically, this anatomical structure permits movement of the ankle about two major axes with respect to the leg: dorsiflexion and plantar flexion occur about an axis which passes transversely through the body of the talus bone, while inversion and eversion occur about a longitudinal axis of the subtalar joint.
It is necessary to condition and rehabilitate the ankle by exercise so that the normal biomechanical movement and function is achieved and maintained. Such exercise is not only necessary to strengthen the muscles, maintain or increase stability of the ligaments and maintain or restore mobility to the ankle joint, but also to retrain the neurological sensors that control and respond to the operation of the other anatomical components. Although some devices for exercising the ankle joint are already known, they are of limited effectiveness and do not operate throughout the full range of mobility of the ankle joint.
For instance, the U.S. Pat. Nos. 3,789,836 to Girten and 3,638,645 to Kitada disclose exercise devices having moving pedals. The pedals move in a single vertical plane and thus are not concerned with mobility of the ankle joint in all directions in which it is anatomically capable of movement. Moreover, these devices are motorized and, therefore, do little to affect the muscular strength or the natural neurological processes which produce and respond to normal biomechanical movements.
Another known ankle exercise device is disclosed in U.S. Pat. No. 3,774,483 to Picolin. Picolin discloses a floormat wherein an upper layer of the floormat is a sinusoidally contoured mat that is attachable to a flat lower mat. The direction and degree of ankle movement is determined by the position at which the foot is placed on the mat and the foot placement positions are not strictly designated on the floor. Thus, Picolin does not disclose an exercise device which is calibrated to produce ankle movements corresponding to normal biomechanical movements of the ankle. Moreover, the foot must be repeatedly removed and repositioned in order to exercise the ankle throughout its normal range of movements.